Setters Formation

Setters Formation
Stratigraphic range: late Precambrian
Outcrop of Setters Formation along Marriottsville Road, Baltimore County
Type	metamorphic
Unit of	Glenarm Group
Underlies	Cockeysville Marble
Overlies	Baltimore Gneiss
Lithology
Primary	Mica-schist
Other	Muscovite-gneiss and quartzite
Location
Region	Piedmont of eastern North America
Country	United States
Extent	Maryland, Pennsylvania, Delaware

The Setters Formation is a geological formation that is located in Maryland, Pennsylvania, and Delaware in the United States. The formation is metamorphic and consists of a complex suite of schist, gneiss, and quartzite. ^[1]

It is the lowest unit of the Glenarm Group (or Supergroup). ^[2] The overlying formations of the group are the Cockeysville Marble and the Wissahickon Formation.

Outcrops

Some outcrops listed by the USGS ^[2] are:

• Setters Ridge, which forms north front of Chattolanee anticline, Baltimore County, Maryland.
• Quarries in Avondale, Pennsylvania.
• Eastburn's quarry, New Castle County, Delaware.

Gallery

• 
  Setters Formation showing schist with tourmaline or hornblende crystals on the foliation plane

References

1. Crowley, William P.; Cleaves, Emery T. (1974). Geologic map of the Towson Quadrangle, Maryland (Map). 1:24000. Maryland Geological Survey.
2. Setters Formation, National Geologic Map Database, Geolex — Unit Summary. Accessed 12 May 2025.